Here's an interesting write up from Phils Blog,
philswindsurfingblog.blogspot.com/2013/09/sail-discussion-vandal-addictsailworks.html This is Dale Cook flying his Hucker in the Gorge. Imagine the explosive acceleration required to propel him to these heights. Imagine also, the control required from the sail to enable one to maintain one's trim while flying in heavy air.
Dale Cook is able to take a break from these jumps, sail round the corner to what they call a speed strip (but is actually just a flattish piece of river interspersed with river traffic and reed beds) and hit speeds of over 40knots in his baggies, his waist harness and this equipment! Absolute magic and a testament to what this type of sail is capable of.